JPH01133027A - Optical parts - Google Patents

Abstract

PURPOSE:To reduce the size of optical parts by forming at least one layer of spiral thin films which are coated with insulating layers and consist of a superconducting material on one main plane of a holding jig and passing electric current to the thin films to generate the magnetic field in parallel with the propagation direction of the incident light on a magneto-optical crystal, thereby generating a magneto-optical effect. CONSTITUTION:The 1st layer of the superconducting layer is formed on the inside wall of the holding jig 110 and is worked to a spiral shape. The 1st layer of the insulating layer 103 and the 2nd layer of the superconducting layer are then successively formed thereon. However,, the end parts 1031, 1032 of the 1st layer of the insulating layer 103 are removed in order to partially conduct the 1st layer and 2nd layer of the superconducting layers. The 2nd layer of the superconducting layer is then worked to the spiral shape and finally the 2nd layer of the insulating layer 1033 is formed. The spiral thin film (superconducting coil) 102 consisting of the superconducting material is formed in such a manner and is made into the two-layered structure with the insulating layer 103 held therebetween. Polarizes 104, 105 are disposed thereto in such a manner that light can pass only from the left to the right. Since the need for using a permanent magnet is thereby eliminated, the size of the optical parts is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to optical components using magneto-optic crystals, such as optical isolators, used in optical communication, optical measurement, and the like.

2. Description of the Related Art In recent technologies such as optical communication and optical measurement, optical components such as optical demultiplexers and wavelength filters are indispensable. Among these, devices using magneto-optic crystals, such as optical isolators and magnetic field sensors, are extremely important because they have the unique function of rotating the plane of polarization in the same direction as the direction of travel, regardless of the direction of light incidence. be. Figure 2 shows an example of a conventional optical isolator (for example, Shibukawa, Iwamura, Katsui, Hayashi et al., Electronics Letters, No. 13, Vol. 24, pp. 721-γ22, 197
7 years) is shown. In the figure, 1 is a garnet crystal (hereinafter referred to as YIG crystal) made of yttrium and iron oxides. Due to the magnetic field applied by the permanent magnet 2, an optical anisotropy called the Faraday effect occurs. The plane of polarization of the generated light rotates. This rotation angle depends on the strength of the magnetic field and YI
It is determined by the optical path length in the G crystal, and is currently set to rotate by 45 degrees. At this time, the light with the plane of polarization selected by the polarizer 5 enters another polarizer 7, but by adjusting the angle of this polarizer, the loss in intensity of the output light 11 relative to the input light 1o is reduced to approximately It can be suppressed to about 1 to 2 decibels. On the other hand, when the above settings are made and the incident light 12 is made to enter from the opposite direction, the light having the polarization component selected by the polarizer 7 will pass through the entire YIG crystal, and the light will pass through the polarizer 5.
The plane of polarization is rotated so that it is perpendicular to the direction of polarization that can pass through. Therefore, the light intensity of the emitted light 13 is very small, and the loss is about 30 decibels compared to that of the incident light 12. The above is the operating principle of the optical isolator.

Problems to be Solved by the Invention However, according to the above configuration, in order to generate a magnetic field of sufficient strength, a permanent magnet with a volume several to ten times as large as that of a YIG crystal is required, and the optical isolator is It was preventing miniaturization. This problem is not limited to optical isolators, but applies to all optical components using magneto-optic crystals.

Means for Solving the Problems In order to solve the problems, the present invention comprises at least a magneto-optic crystal and a holding jig attached to cover the side surface of the magneto-optic crystal, the holding jig A magnetic field parallel to the propagation direction of light incident on the magneto-optic crystal is generated by forming at least one spiral thin film made of a superconducting material and covered with an insulating layer on one principal surface and passing a current through the thin film. The object of the present invention is to provide an optical component that is characterized in that it causes magneto-optical effects.

Effects According to the above-described configuration, it is possible to reduce the size of the optical component since it is not necessary to use a permanent magnet. In addition, since the superconducting material is completely bent, if a current is generated at the time of shipment, the current will continue to flow permanently after that, so there is no need for a permanent T source or the like. Furthermore, since the length at which a spiral can be formed can be longer than that of a magneto-optic crystal, the magnetic field in the magneto-optic crystal can be made more uniform than in the past.

Embodiment FIG. 1 is a sectional view of an embodiment of the present invention, taking an optical isolator as an example. 101 is a YIG crystal. 1
02 is, for example, strontium-doped Y, Ba2Cu3
0. A spiral thin film emitted from a superconducting material called -8 (hereinafter referred to as
It is called a superconducting coil. ), an insulating layer 1 consisting of 5in2
It has a two-layer structure with 03i in between. A method for manufacturing a superconducting coil will be described below. First, a first superconducting layer is formed on the inner wall of the holding jig 110 by sputtering or the like.

This layer is processed into a spiral shape using a precision lathe. Next, a first insulating layer 103 and a second superconducting layer are sequentially formed by sputtering. However, in order to partially conduct the first and second superconducting layers, the ends of the first insulating layer 103 are removed as shown in 1031 and 1032. Next, the second superconducting layer is processed into a spiral shape using a precision lathe, and finally the second insulating layer 1o33 is formed. The superconducting coil created in this way has an electrically closed loop. Therefore, when a wire is broken at one point, a power supply is connected, a direct current is applied, and the broken wire is repaired using a superconducting material, a steady magnetic field appears around the holding jig 11o because the current continues to flow through the coil. This magnetic field is near the YIG crystal 101,
Since they are approximately parallel to each other, the Faraday effect also occurs uniformly in the crystal, making it easy to estimate the relationship between crystal dimensions and rotation angles.

The rotation angle of the polarization plane is determined by the length of the YIG crystal, the amount of current flowing through the coil, and the number of turns of the coil.

In this case, the rotation angle is set to 45 degrees, and the polarizers 104 and 105 are arranged so that light can pass only from left to right.

Similarly, in this example, the superconducting coil has a two-layer structure, but one
There is no problem with a layer or three or more layers. Furthermore, although this embodiment takes an optical isolator as an example, the present invention is not limited to optical isolators. In addition, this Example 2
is formed on the inner wall of the entire superconducting coil 102 holding jig 110, but there is no problem if it is formed on the outer wall.

Effects of the Invention According to the present invention, since permanent magnets are not required, the number of parts can be reduced and the assembly process can be simplified.

Additionally, since superconducting materials are used in the coils, large currents can be passed through them, making it possible to generate strong magnetic fields.

Furthermore, the magnetic field can be easily strengthened by increasing the number of turns of the coil. Furthermore, by changing the shape of the holding jig, the magnetic field distribution can be easily optimized.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the entire structure of an optical component according to an embodiment of the present invention, and FIG. 2 is a sectional view showing the structure of a conventional optical component. 101... YIG crystal, 102... Thin spiral pattern, 103... Insulating layer, 110...
...Holding jig. 104.105...Polarizer.

Claims (1)

[Claims] a magneto-optic crystal; a first helical layer fixed to the magneto-optic crystal and having at least one layer made of a superconducting material on one main surface;
and at least one second thin film made of an insulator covering the surface of the first thin film. An optical component whose direction is parallel to the traveling direction of light passing through the magneto-optic crystal.